1. Field of the Invention
This invention relates to folding support structures and more particularly to support systems for child strollers and chairs.
2. General Background and State of the Art
Folding structures of the type adapted to support an object or a person are well known in the art. Most of these structures fold only in one dimension, resulting in a rather bulky configuration when considering ease of storage and transportation. Others fold in multiple dimensions, but do not provide adequate seat and back support for an occupant seated in the structure.
Some folding structures include wheels to facilitate movement of the structure when it is supporting a person, such as baby carriages or strollers having wheels for ease of movement of the stroller and its occupant. A typical example of this type configuration is described in U.S. Pat. No. 3,390,893 directed to structures for folding baby carriages, chairs, and the like.
Some existing structures include X frames which are pivotally connected by means of pivot joints, the frames being held in their unfolded position at a fixed angle with respect to each other by rigid brace members pivotally connected to the frames. One X frame is usually more or less vertical and located at the back of the structure, while the other is at the bottom of the structure and is generally horizontal in its unfolded position. In its folded configuration, the two X frames collapse and all elongated elements thereof are nearly parallel. The brace elements also fold about pivoted interconnections so that the ends of the X frames come together. This moves the front wheels near the location of the carriage's handles where they may soil clothes, for example, and, because of this elevated mass, a clip is required in order to retain the structure in a folded position. Thus, it should be evident that a foldable support structure that is simple in construction and that folds into a slim configuration while maintaining a low center of mass with all wheels always located near the ground level and that does not require a clip mechanism to hold the structure in its folded position, and that provides sturdy support for a seated occupant, would constitute a significant advancement of the art.
In U.S. Pat. No. 3,995,882, a folding structure in one embodiment includes ground wheels and handles to form a child's stroller, the structure having a pair of elongated frame tubes that are laterally foldable and held together at two spaced points on each of the tubes by pivotally connected front and rear X braces, the structure also including a pair of elongated seat tubes pivotally attached to main frame tube-supported folding mechanisms that allow the seat tubes to move upwardly and in closer angular alignment with the main frame tubes when the latter move closer together as the structure is changed from its unfolded to folded configuration, resulting in a folded cross-sectional area not much greater than the sum of the cross-sectional areas of the individual members.
The folding structures described above do not provide for a sturdy back support for children or adults seated in the chair. Therefore, there is a need in the art for a folding support structure with a sturdy back support that is capable folding into a compact configuration for ease of storage and transportation, such as in both a side-to-side and a front-to-back manner.